I have a 2x20 LCD display type LM032L with HD44780A chip.This display has no backlight.

When i send text to the display it is only displayed when there is a lcd.clear();before the text line.When the second message is send i see only trange characters, when i put again a lcd.clear before the message it is displayed alright.

I have send the software code for photoduino to the Arduino one v3, and there it is the same, but i cannot put everywhere in the code this lcd.clear() command.

That is really the only explanation since I know that the code is correct and we also know that your wiring is correct since most of the message is displayed correctly. Some of the bargain displays being sold are probably ones that don't quite meet the factory specs.

It looks like your display may be taking too long to complete the commands in the lcd.begin() function so it is missing the first letter sent to it by the lcd.print() function. You could stick a 10 mS delay in before the lcd.print() function and see if that helps.

There is nothing sacred about the pins used in the example. It is, however, important to make sure that the code matches the wiring which is why we frequently ask for both the code and a photograph of the wiring when troubleshooting.

Did you read reply #7? Since he does get a valid display some of the time we know that his wiring does match his code so the problem must be elsewhere else.